Air suspensions and air brakes are widely used in the commercial trucking industry. These systems may be fed by pressurized air from the brake system of an attached tractor through a system of conduits and control valves. However, gate or rear platforms are typically lifted or pivoted by electric-over-hydraulic mechanisms, which have substantial drawbacks.
Rear platforms or lift gates on tractor trailers provide a mechanism for transporting loads on and off of the trailers. Conventional systems for lifting rear platforms may utilize pneumatic cylinders or a chain mechanism to provide the power to lift the platform. However, chain mechanisms require a driving motor and pneumatic cylinders cannot be provided with sufficient power from an air suspension and/or air brake system of a typical tractor to lift the rear platform, and thus also require a separate driving motor. These systems typically require the truck to be running to supply power to the driving motor, or the driving motor is powered by batteries tied into the electrical system of the tractor.
Such systems present distinct disadvantages including: 1) the risk that the batteries may die or lose charge (or the need to keep the truck running to supply power), 2) the batteries and/or driving motors add weight to the trailer; 3) extensive maintenance is generally required; 4) environmental contamination may be caused from hydraulic fluid leaks in such systems, and 5) the systems are expensive. With new regulations and environmental concerns, these existing systems are becoming less desirable, less reliable, and less effective. For example, multiple stops and uses of the batteries may drain them of charge, leaving the lift mechanisms inoperable, and local and state laws may prohibit idling of the truck and thus prevent the driver from recharging the auxiliary batteries during a stop. Thus, conventional lift mechanisms can fail under certain circumstances.
It is therefore desirable to provide improved lifting and positioning systems for trailer platforms and trailer systems. The present invention provides such apparatuses and methods of using the same, while at the same time accomplishing many of the desirable conditions described below.